The Democratic front-runner swept the South in this winter's primaries and caucuses -- piling up massive numbers of convention delegates in the power base of her Republican rivals. The top Republican candidate won liberal Massachusetts and industrial Illinois and Michigan -- prevailing in states the Democrats have won in every election since 1992 and the party's power base in the 21st century.

The party that claimed younger voters and planned to use their loyalty to remain in the White House for a generation is about to nominate a presidential candidate who is 68 and has consistently lost the support of young voters to a 74-year-old challenger. The party that seemed demographically doomed because of its failure to win support from Hispanics had two Cuban-Americans as leading candidates this year, with one of them emerging as the likeliest challenger to Manhattan businessman Donald J. Trump.

The likely presidential nominee of the progressive party is conservative in style and outlook. The front-runner of the conservative party is radical in campaign style and political outlook.

The party that is the natural combatant to the banks and to Wall Street is about to nominate a candidate who has taken hundreds of thousands of dollars from those very interests. The party that is the natural party of business could nominate a real-estate tycoon whose emphasis is on middle-class jobs, who is contemptuous of the financial elite and who flaunts his use of eminent domain, a potent symbol of big-government power that business interests and conservatives revile.

Suddenly it is becoming clear that this year's election is an upside-down cake being served to a reluctant electorate.

And as slices of that cake are carved, it is apparent that geopolitical assumptions that have governed American politics since the Nixon years are being rendered obsolete, replaced by new assumptions that have a new logic and that promise a new political calculus.

This year some of the most reliably Republican states in the Union -- Utah and Idaho, both of which have consistently voted Republican since 1952 with the exception of the Barry Goldwater debacle in 1964 -- are suddenly plausible pick-ups for the Democrats.

These are the two states with the highest percentages of Mormon voters, at once the most reliably Republican voting group and the group most antagonistic to Trump. The billionaire businessman's life and campaign style are incongruous in Mormon circles, and he antagonized many Mormons when he ridiculed former GOP Gov. Mitt Romney of Massachusetts, the first Mormon presidential nominee.

Now consider two important Southern states. Since 1964, Georgia has voted Democratic only when a native son (Jimmy Carter) and a Southerner (Bill Clinton in 1992, but not when he ran for re-election in 1996) were on the top of the ticket. Since 1968, North Carolina has voted Democratic only twice, when Carter was on the ballot in 1976 (but not when he ran for re-election in 1980) and in 2008 (when Barack Obama took the state by three-tenths of a point, a feat he did not repeat in 2012).

And yet neither is safe for the Republicans if Trump is nominated. Nor is the bellwether state of Florida, which Trump claims as one of his homes and which, with the exception of 1960 and 1992, has sided with the winner every time since 1928.

In fact, neither party can completely count on its traditional constituencies.

Mainline Protestants, for generations the mainstays of the GOP, showed little interest in voting for Trump in the primary in Massachusetts, where they traditionally have supplied and supported Republican candidates.

Yet some states, like Michigan, which has voted Democratic in the last six presidential elections, now may be ripe for the Republicans if Trump is the nominee.

Michigan has the classic Rust Belt profile; Bureau of Labor Statistics figures show the state shed 231,752 manufacturing jobs, or about a quarter of its manufacturing work force, since the 1994 implementation of the North American Free Trade Agreement, a principal Trump target. Though the devaluation of the peso in Mexico's 1994 currency crisis may have been as much a factor in the job losses, the trade agreement remains under fire in Michigan.

Trump was the decisive victor in last month's Michigan Republican primary among voters whose incomes fall below $50,000 -- voters who otherwise would be considered natural constituents of the Democrats. Because Democrats with the same income levels did not exactly flock to former Secretary of State Hillary Clinton, who in the Michigan Democratic primary narrowly lost that group to Sen. Bernie Sanders of Vermont, they, too, can be considered vulnerable to Trump's entreaties.

And though polls show Clinton with a comfortable lead in Pennsylvania, which has voted Democratic in the last six elections and where Clinton defeated Obama by 10 points eight years ago, both Clinton and Trump have high unfavorable ratings, according to the Franklin and Marshall College Poll. Many analysts believe the state is up for grabs.

Meanwhile, Republicans increasingly believe that Maine, which has gone Democratic in the past six elections, is within their reach, particularly since the state awards one electoral vote to the candidate who wins each of the two congressional districts. Paul LePage, the controversial Republican governor of Maine, has endorsed Trump.

Then there is the question of New York, which Clinton represented in the Senate and which has voted Republican only three times in the 14 elections since 1960. That is Trump's true home state, and GOP strategists believe that, despite a large Clinton lead, they may be able to prevail there in the fall.

Another crucial battlefield will be Wisconsin, which holds its highly contentious primary Tuesday. The state has been safely Democratic the past seven elections and early indications suggest Clinton has an edge there. But that could change if Trump prevails in the state this week; he is running behind Cruz, according to a Marquette Law School statewide poll late last week.

Taken together, all these moving parts are creating a complex new math and a vital new truth: In an era when so many Americans believe American politics needs to be fixed, there are no fixed points in American politics.

David Shribman, a Pulitzer Prize winner in journalism, is executive editor of the Pittsburgh Post-Gazette.